"You've got a great waist-to-hip ratio," my date declared, after which he went on to explain that men have biologically evolved to respond to just the right womanly proportions and also to react to large breasts, since both of these signify fertility. My date was not an evolutionary scholar, or a scholar of any kind. He was just a regular guy who, like so many others, had been exposed to and internalized popular magazine articles and television news programs that champion the science of evolutionary psychology.

Evolutionary psychology uses contemporary Darwinian theory to explain, among other things, how human males and females evolved with different sexualities or, in the jargon of evolutionary psychologists, different "sexual psychologies." Read: men and women want different things in a mate and have different sexual styles. While the fairer sex is choosey about her mates, more capable of a lasting bond with a lover, and dedicated to her role as a parent, the harrier sex is sexually promiscuous, places an enormous emphasis on women's youth and beauty (which he ogles every chance he gets), either cheats on his wife or wants to, and can be sexually aggressive to the point of criminality.

Evolutionary theorists interested in human behavior reason that our human male ancestors were, back in the environment to which our bodies are adapted, constantly competing with one another for sexual access to fertile women. Evolution favored women who were picky about their mate choices, given the high level of parental investment required of the human female for reproduction -- months of gestation, giving birth, and then years of lactation and care for a dependent child. The human male's low level of parental investment required for reproduction -- after all, he need only ejaculate into a fertile body to reproduce and could father hundreds of children -- meant that human males evolved to be relatively sexually carefree or, less delicately, to be, by nature, wanton skirt chasers.

But having briefly outlined the evolutionary theoretical approach to sex differences in human sexual behavior, I want to talk about the popular spread of that theory, however distorted or watered down it winds up. For we find references to man's evolutionary heritage throughout popular culture -- in new science textbooks, pop psychology books on relationships, men's magazine, and even on T-shirts. (Picture the frat dude chugging a beer in a shirt with a picture of a caveman clad in a fur pelt holding a club and with the statement "Me Find Woman." You can actually buy these shirts on cafepress.com.) There are caveman fitness plans and caveman diets. Saturday Night Live's hilarious "Unfrozen Caveman Lawyer" and the affronted caveman of the Geico car insurance ads joke about the ubiquity of caveman narratives. More disturbingly, the Darwinian discourse also crops up when men need an excuse for antisocial behavior. One man, who was caught on amateur video participating in the Central Park group sexual assaults in the summer of 2000, can be heard on video telling his sobbing victim, "Welcome back to the caveman times."

Popularized evolutionary discourse, or pop-Darwinism, offers men a scientifically authorized way to think about -- and live out -- their sexuality. Indeed, popular attention to the evolution of human male sexuality has increasingly lodged American manhood in an evolutionary logic. Pop-Darwinism has become a sort of cultural consensus about who men are. Average American guys don't read academic evolutionary science, but many do read about science in popular magazines and in bestselling books written by enthusiasts of evolutionary psychology. Popular culture is a political Petri dish for Darwinian ideas about sex. As such, it is worth examining -- even when magazine writers and television producers intentionally "dumb down" or distort more sophisticated or modest academic claims.

An issue of Men's Health magazine explains "the sex science facts" to male readers interested in "the biology of attraction." We follow the steps of a mating dance, but don't quite understand that's what we're doing. Indeed, we must learn the evolutionary history of sex to see why men feel the way they do when they notice a beautiful woman walking down the street:

Of course, out there in the street, you have no thoughts about genetic compatibility or childbearing. Probably the farthest thing from your mind is having a child with that beautiful woman. But that doesn't matter. What you think counts for almost nothing. In the environment that crafted your brain and body, an environment in which you might be dead within minutes of spotting this beauty, the only thing that counted was that your clever neocortex -- your seat of higher reason -- be turned off so that you could quickly select a suitable mate, impregnate her, and succeed in passing on your genes to the next generation.

The article, "The Biology of Attraction" by Laurence Gonzales, proceeds to identify the signals of fertility that attract men: youth, beauty, big breasts, and a small waistline. Focusing on the desire for youth in women, the article tells men that "the reason men of any age continue to like young girls is that we were designed to get them pregnant and dominate their fertile years by keeping them that way ... When your first wife has lost the overt signals of reproductive viability, you desire a younger woman who still has them all." And, of course, male readers are reminded that "your genes don't care about your wife or girlfriend or what the neighbors will say."

Men, the popular account of evolution tells us, are rampantly heterosexual skirt chasers. (Anyone who's gay serves, at best, as evidence of the supposedly nonadaptive delights in which some humans indulge and, at worst, as evidence of what is unnatural and therefore immoral.) This understanding of male sexuality helps fuel a culture Michael Kimmel recently labeled "guyland," the life stage and social space in which teenage and twenty-something men cultivate a rude-dude attitude, resenting anything intellectual, politically correct, or smacking of either responsibility or women's authority. What better than the caveman narrative to help these guys avoiding the demands of adult life define themselves as, nevertheless, real men?

Learning evolution's significance for male sexuality can enable men to rationalize sexist double standards and wallow in their loutishness, as they do in guyland. Alternatively, it can serve to encourage men to control their caveman natures by becoming self-conscious, enlightened cavemen. But either way, the popular versions of man-as-caveman never question men's putatively natural shortcomings or innate aggressive heterosexuality. The caveman is certainly not the only form of masculine identity in our times. But the emergence of a caveman masculinity tells us much about the authority of science, the flow of scientific ideas in our culture, and the embodiment of those ideas. We live in a culture attached to scientific authority and explication. The popularity of the scientific story of men's evolved desires -- however distorted the science becomes as enthusiasts popularize it -- can tell us something about the appeal and influence of that story.

The influence of the evolutionary story cuts right to men's physically felt dispositions. In his book, Cultural Boundaries of Science, Thomas Gieryn comments on the cultural authority of science, suggesting that "if 'science' says so, we are more often than not inclined to believe it or act on it -- and to prefer it to claims lacking this epistemic seal of approval." To his observation I would add that we are also more likely to live it. Ideas that count as scientific, regardless of their truth value, become lived ideologies. In this way, a heterosexist form of male sexuality is naturalized. In her discussion of naturalizing male power, sociologist Raewyn Connellstates:

The physical sense of maleness is not a simple thing. It involves size and shape, habits of posture and movement, particular physical skills and the lack of others, the image of one's own body, the way it is presented to other people and the ways they respond to it, the way it operates at work and in sexual relations. In no sense is all this a consequence of XY chromosomes, or even of the possession on which discussions of masculinity have so lovingly dwelt, the penis. The physical sense of maleness grows through a personal history of social practice, a life-history-in-society. (Gender and Power: Society, the Person and Sexual Politics)

We see and believe that men's power over women is the order of nature because, as Connell puts it, "power is translated not only into mental body-images and fantasies, but into muscle tensions, posture, the feel and texture of the body." The caveman becomes an imaginative projection that is experienced and lived as real biological truth.

We must challenge the convenient innocence with which men invoke science to understand and experience their bodies. The caveman mystique is, after all, a contemporary male counterpart of the feminine mystique so famously described by Betty Friedan in 1963. Women had to challenge the popular idea that they found fulfillment in keeping house and rearing children. It's time now to challenge the idea that men find true self-expression in boorish behaviors, sexual aggression, and chance sexual encounters. Indeed, it's time for men to take a great leap forward to develop a more sociological understanding of both science and their own sexuality.

Martha McCaughey is Professor of Womenâ€™s Studies and Sociology at Appalachian State University. She is the author of The Caveman Mystique: Pop-Darwinism and the Debates Over Sex, Violence, and Science (Routledge, 2008). Her research interests include gender, science, technology, and the body.